Title

Presenter Information

Document Type

Oral Presentation

Location

SURC 137B

Start Date

21-5-2015

End Date

21-5-2015

Keywords

Invasive Plants, Allelopathy, Knapweed

Abstract

Invasive plants decrease native plant diversity and alter ecosystem structure and function, and controlling their spread represents a significant cost to taxpayers. Most exotic species are not invasive in their native range, so successful invasive management requires understanding the biological mechanisms that allow exotic plants to gain advantage over native plants and become invasive. The Novel Weapons Hypothesis postulates that exotic plant exudates, compounds released from plant roots, have an allelopathic effect on native plants that reduces their fitness and decreases their ecological success. The allelopathic compounds could thus allow an exotic plant to become a superior competitor over native species and reach invasive status. Spotted knapweed (Centaurea stoebe), an introduced European annual, produces the racemic chemical (±)-catechin, which has allelopathic qualities on the native grass Idaho fescue (Festuca idahoensis), although the severity of the allelopathy is contentious and uncertain. Much research has focused on extreme (±)-catechin concentrations unlikely to be found in nature, but instead, we tested the dose-dependent effects of environmentally relevant (±)-catechin concentrations on root growth of Idaho fescue. Using germination paper, three replicates of 120 Idaho fescue seeds were placed into rows and grown in (±)-catechin solution concentrations of 20 ppm and 80 ppm. Catechin was found to significantly inhibit root growth in both concentrations compared to control solutions of water, t test, p<0.05. This finding supports the Novel Weapons Hypothesis by offering evidence of spotted knapweed’s allelopathic nature at environmentally relevant (±)-catechin concentrations, and it offers insight into proactive invasive plant management.

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Invasive plants decrease native plant diversity and alter ecosystem structure and function, and controlling their spread represents a significant cost to taxpayers. Most exotic species are not invasive in their native range, so successful invasive management requires understanding the biological mechanisms that allow exotic plants to gain advantage over native plants and become invasive. The Novel Weapons Hypothesis postulates that exotic plant exudates, compounds released from plant roots, have an allelopathic effect on native plants that reduces their fitness and decreases their ecological success. The allelopathic compounds could thus allow an exotic plant to become a superior competitor over native species and reach invasive status. Spotted knapweed (Centaurea stoebe), an introduced European annual, produces the racemic chemical (±)-catechin, which has allelopathic qualities on the native grass Idaho fescue (Festuca idahoensis), although the severity of the allelopathy is contentious and uncertain. Much research has focused on extreme (±)-catechin concentrations unlikely to be found in nature, but instead, we tested the dose-dependent effects of environmentally relevant (±)-catechin concentrations on root growth of Idaho fescue. Using germination paper, three replicates of 120 Idaho fescue seeds were placed into rows and grown in (±)-catechin solution concentrations of 20 ppm and 80 ppm. Catechin was found to significantly inhibit root growth in both concentrations compared to control solutions of water, t test, p<0.05. This finding supports the Novel Weapons Hypothesis by offering evidence of spotted knapweed’s allelopathic nature at environmentally relevant (±)-catechin concentrations, and it offers insight into proactive invasive plant management.